This invention relates to closure plug assemblies for sealing fluid conduits. More particularly, the plug assembly of this invention is used for pressure testing of fluid drain and vent systems. The plug assembly is used for sealing sections of connecting conduits such as a Y or T connection and is also adapted to sealing off an open end of an incomplete pipeline.
It is common in the plumbing industry to test drain and vent systems for possible leakage. It is necessary to seal an installed pipeline and apply a predetermined fluid pressure therein. There are several known devices and assemblies available for accomplishing this purpose.
To test for leaks in the drainage system, an inflatable ball is inserted in the line through either a T or Y connection. Once in place, the ball is inflated in the line. However, the prior art testing devices have a ball that can easily slip under the fluid pressure. If it does slip, it will be pushed down the line where it will cause a complete stoppage of the system. It may very well be necessary to break up the building construction around the installed plumbing in order to retrieve the ball that has slipped. To keep the ball of the prior art device from slipping, it is a common practice to overinflate this ball within the line. Thus, an attempt is made to withstand the fluid pressure as well as seal the pipeline. Under these circumstances, the overinflated ball often bursts and is then caused to slip down the line.